PB2270: PROGNOSTIC VALUE OF INTERIM POSITRON EMISSION TOMOGRAPHY IN HIGH-TUMOR-BURDEN FOLLICULAR LYMPHOMA
Authors: Marta Mora Argumánez, Rocio Perez, Beatriz Alvarez Padilla, María Irene Nuevo López, Angela Gil, Dolores Subirá Pérez, Ana Belén Santos Montero, Nuria Golbano, Helga Guillén García, Alejandro Vazquez Ramo, Sonia Herrero Martín, Laura Moreno, Jaime Arbeteta Juanis, María Dolores Morales Sanz, Dunia De Miguel Llorente
Journal: HemaSphere (2023)

Topic: 18. Indolent and mantle-cell non-Hodgkin lymphoma - Clinical Background: Interim Positron Emission Tomography (I-PET) has shown to have a high prognostic value in high-grade lymphomas. However, the prognostic value of I-PET during treatment for follicular lymphoma (FL), a disease characterized by frequent relapses and remissions, has not been standardized due to a lack of clear evidence. Aims: This study aims to determine the prognostic value of I-PET for high-tumor-burden FL. Methods: This retrospective cohort study included FL patients who received chemotherapy at Hospital de Guadalajara from 2013 to 2022 and underwent I-PET imaging after the 4th cycle of treatment. Patients with 3B histological grade were excluded. Using Cox regression model, Kaplan-Meier survival curves, and Log-rank test, we analyzed the I-PET and final PET (F-PET) responses in patients who underwent chemotherapy for FL. The primary endpoints were progression-free survival (PFS), overall survival (OS), and recurrence within 24 months (POD24). Results: A total of 35 patients (48.6% women) with a median age of 58 years were included. Patients received immunochemotherapy with R-CHOP (17) or R-Bendamustine (18) and underwent I-PET imaging after 3 cycles (2.8%) or 4 cycles (97.1%) and F-PET at the end of treatment. Treatment regimens were not modified based on I-PET results. In 62.9% of patients, I-PET showed complete remission (CR), while the remaining patients exhibited partial remission (PR) or progression. Similarly, F-PET showed CR in 77.1% of patients. The median follow-up period was 48.8 months (range: 5.06-114.72). During that period, 11.4% (4) of patients died and 22.9% (8) relapsed. OS and PFS were not reached. Patients who achieved CR based on I-PET results had a significantly longer PFS than those who did not (p=0.016), but no significant differences were observed in OS (p=0.255). Additionally, patients who did not achieve CR based on I-PET results but achieved CR based on F-PET results had a significantly shorter PFS than those who achieved CR based on both I-PET and F-PET results (p=0.018). There were no significant differences in PFS for patients who did not achieve CR based on F-PET results, regardless of their I-PET results (p=0.117). There were no statistically significant differences in the incidence of POD24 based on I-PET results (p=0.102). When comparing the three patient groups (I-PET PR + F-PET CR vs I-PET CR + F-PET CR vs F-PET PR), the group that achieved CR based on I-PET results and maintained it at the end of treatment showed a significantly longer PFS (p=0.004). Summary/Conclusion: I-PET predicts a higher PFS in patients who achieve CR based on both I-PET and F-PET results, but it has no significant prognostic value for OS. Further studies to evaluate the modification of treatment based on I-PET results could be useful to prevent relapses in FL patients.Keywords: Prognosis, Follicular lymphoma, Positron emission tomography (PET)